Measurement and Instrument

Ohm Meter -Equivalent Circuit-

Ohm Meter -Operational Theory-

Ohm Meter -Example- A 50 Ω basic movement requiring a full scale current of 1 mA is to be used as an ohmmeter. The internal battery voltage is 3 V. A half scale deflection marking desired is 1000 Ω. Calculate i)Value of R 1 and R 2 ii)Maximum value of R 2 to compensate for a 5% drop in battery voltage

Ohm Meter -Wheatstone Bridge (Balanced) -

Ohm Meter -Wheatstone Bridge (Unbalanced)-

Ohm Meter – Wheatstone Bridge -Example-

Ohm Meter – Wheatstone Bridge -Solution-

Energy Meter - CT and PT -

Energy Meter - CT and PT in Energy Measurement -

Energy Meter - Example - Exp1: A 250 : 5, current transformer is used along with an ammeter. If ammeter reading is 2.7 A, estimate the line current. Exp2: A : 110, potential transformer is used along with a voltmeter reading 87.5 V. Estimate the value of line voltage.

Rectifier Instruments - AC Voltmeter -

Peak value Peak to peak value r.m.s.value Average value Form factor Rectifier Instruments - Parameters -

Rectifier Instruments - Operational Theory -

An ac voltmeter uses half wave rectifier and the basic meter with full scale deflection current of 1 mA and the meter resistance of 200 ohm. Calculate the multiplier resistance for a 10 V rms. Range on the voltmeter. An ac voltmeter uses a full wave bridge rectifier and the basic meter with full scale deflection current of 2 mA and the meter resistance of 500 ohm. Calculate the multiplier resistance for a 10 V r.m.s range on the voltmeter. Rectifier Instruments - Example -

1.Function/Range Switch: selects the function (voltmeter, ammeter, or ohmmeter) and the range for the measurement. 2. COM Input Terminal:Common ground, used in ALL measurements. 3. V Input Terminal: for voltage or resistance measurements mA Input Terminal: for small current measurements A Input Terminal: for large current measurements. 6. Low Battery LCD: appears when the battery needs replacement. Multimeter

DVM Non-Integrating type Integrating type Potentiometric type Ramp type Voltage to frequency converter type Potentiometric type Dual slope integrating type

Power Factor Meter